The present invention relates to a use of a composition. In particular, the present invention relates to a use of a pectin composition.
Pectin is an important commodity in today""s industry. For example, it can be used in the food industry as a thickening or gelling agent, such as in the preparation of jams or fruit systems for yoghurt.
Pectin is a structural polysaccharide commonly found in the form of protopectin in plant cell walls. The backbone of pectin comprises xcex1-1-4 linked galacturonic acid residues which are interrupted with a small number of 1,2 linked xcex1-L-rhamnose units. In addition, pectin comprises highly branched regions with an almost alternating rhamno-galacturonan chain. These highly branched regions also contain other sugar units (such as D-galactose, L-arabinose and xylose) attached by glycosidic linkages to the C3 or C4 atoms of the rhamnose units or the C2 or C3 atoms of the galacturonic acid units. The long chains of xcex1-1-4 linked galacturonic acid residues are commonly referred to as xe2x80x9csmoothxe2x80x9d regions, whereas the highly branched regions are commonly referred to as the xe2x80x9chairy regionsxe2x80x9d.
Some of the carboxyl groups of the galacturonic residues are esterified (e.g. the carboxyl groups are methylated). Typically esterification of the carboxyl groups occurs after polymerisation of the galacturonic acid residues. However, it is extremely rare for all of the carboxyl groups to be esterified (e.g. methylated). Usually, the degree of esterification will vary from 0-90%. If more than 50% of the carboxyl groups are esterified then the resultant pectin is referred to as a xe2x80x9chigh ester pectinxe2x80x9d (xe2x80x9cHE pectinxe2x80x9d for short) or a xe2x80x9chigh methoxyl pectinxe2x80x9d. If less than 50% of the carboxyl groups are esterified then the resultant pectin is referred to as a xe2x80x9clow ester pectinxe2x80x9d (xe2x80x9cLE pectinxe2x80x9d for short) or a xe2x80x9clow methoxyl pectinxe2x80x9d. If 50% of the carboxyl groups are esterified then the resultant pectin is referred to as a xe2x80x9cmedium ester pectinxe2x80x9d (xe2x80x9cME pectinxe2x80x9d for short) or a xe2x80x9cmedium methoxyl pectinxe2x80x9d. If the pectin does not contain anyxe2x80x94or only a fewxe2x80x94esterified groups it is usually referred to as pectic acid.
LE pectins have for a long time been used in yoghurt fruit as a stabilising agent to ensure a certain yield stress and consequently uniform distribution of fruit without giving a too high viscosity. However, LE pectins tend to form a gel and any gelation should be avoided.
Gelation is detrimental to the appearance of many food products and may also result in undesirable organoleptic properties. Gelation of a product may also prohibit the pumping of that product. Pumping is a widely used method for manipulating products during manufacture and application, and consequently pumpability is a demand in many applications, e.g. yoghurt fruit application.
The prior art has attempted to overcome the above problems. The prior art has provided xe2x80x9cpregelledxe2x80x9d systems which although they may overcome some of the above problems, produce a product which is grainy with a dull appearance. Furthermore, such pregelled products has a strong tendency to syneresis.
The present invention aims to overcome the problems of the prior art.
According to a first aspect of the present invention there is provided use of a pectin composition to prepare an aqueous composition having high yield stress characteristics without substantial gelation, wherein the pectin composition comprises at least a population of pectin that is calcium sensitive; wherein the pectin composition is capable of imparting high yield stress characteristics to an aqueous composition without causing substantial gelation of the aqueous composition.
The present invention is advantageous in that it may provide an aqueous composition which is smooth and shiny in appearance without exhibiting syneresis, in contrast to the pre-gelled systems of the prior art.
The term xe2x80x9cpectinxe2x80x9d includes fractions of pectin, one or more compounds from the class of compounds known as pectins, and derivatives thereof.
The term xe2x80x9cderivatives thereofxe2x80x9d includes derivatised pectin and degraded pectin (such as partially degraded pectin) and modified pectin.
The term xe2x80x9cpopulation of pectin that is calcium sensitivexe2x80x9d means a population of pectin which has a calcium sensitivity index (CF) not equal to 1. A Protocol for determining calcium sensitivity may be found on page 57 of WO-A-97/03574 (the contents of which are incorporated herein by reference). For ease of reference, this Protocol is recited at the end of the Examples section (infra) as Protocol I.
Preferably, the population of pectin has a CF of greater than 1.2. More preferably, the population of pectin has a CF of greater than 5. Yet more preferably, the population of pectin has a CF of greater than 15.
Preferably, the pectin composition has a CF of greater than 1.2. More preferably, the pectin composition has a CF of greater than 5. Yet more preferably, the pectin composition has a CF of greater than 15.
In the present specification, by the term xe2x80x9chaving a high yield stressxe2x80x9d it is meant that the yield stress of the aqueous composition as measured in accordance with the Protocol II is at least 1.0 Pa. Protocol II is recited at the end of the Examples section (infra).
Preferably, the yield stress of the aqueous composition is greater than 3.0 Pa. Yet more preferably, the yield stress of the aqueous composition is greater above 5.0 Pa.
In the present specification, by the term xe2x80x9cwithout substantial gelationxe2x80x9d it is meant that the maximum viscosity of a standardised aqueous composition measured in accordance with the Protocol III is no greater than 500 Pa. Protocol III is recited at the end of the Examples section (infra).
Preferably, the pectin composition is capable of imparting a high degree of shear thinning to an aqueous composition. A high degree of shear thinning is an important theological characteristic in liquid and semi-liquid systems to facilitate pumping and to secure a good non-sticky mouthfeel.
The degree of thixotropy of the aqueous composition may be varied from application to application. If stabilisation of suspended particles is required, the aqueous composition is preferably able to build up structure after shearing with low thixotropy. If a degree of flow after shearing is required, a degree of thixotropy is desirable and may be provided by the pectin composition. The pectin composition may be used in accordance with the present invention to control the above rheological characteristics. This control may be achieved by controlling, among other things, the degree of esterification (% DE), the proportion of the pectin composition which is calcium sensitive (% CSP), the calcium sensitivity of the calcium sensitive population of pectin (CS), the molecular weight of the pectin composition and/or the concentration of calcium in the aqueous composition.
Degree of thixotropy, shear thinning and shear reversibility may be evaluated by performing a flow curve experiment in accordance with Protocol IV. Protocol IV is recited at the end of the Examples section (infra).
Preferably, the aqueous composition has a low viscosity at a shear rate of 0.1 sxe2x88x921.
In the present specification, by the term xe2x80x9clow viscosityxe2x80x9d it is meant that the viscosity at a shear rate of 0.1 sxe2x88x921, measured in accordance with Protocol IV, is less than 100 Pa.s, preferably less than 80 Pa.s.
Thus, in a second aspect the present invention provides use of a pectin composition to prepare an aqueous composition having high yield stress characteristics and a low viscosity at a shear rate of 0.1 sxe2x88x921, wherein the pectin composition comprises at least a population of pectin that is calcium sensitive; wherein the pectin composition is capable of imparting to an aqueous composition high yield stress characteristics and a low viscosity at a shear rate of 0.1 sxe2x88x921.
The calcium sensitive pectin population can comprise any one or more of a low ester pectin, a medium ester pectin or a high ester pectin. Preferably, the calcium sensitive pectin population comprises a high ester pectin. Preferably, the calcium sensitive pectin population does not comprises a low ester pectin or a medium ester pectin.
Preferably, the degree of esterification of the calcium sensitive pectin population is from 50 to 90%. More preferably, the degree of esterification is from 60 to 85%. More preferably, the degree of esterification is from 60 to 80% or 65 to 85%. Yet more preferably, the degree of esterification is from 65 to 80%.
Preferably, the degree of esterification of the total pectin composition is from 50 to 90%. More preferably, the degree of esterification is from 60 to 80% or 65 to 85%. Yet more preferably, the degree of esterification is from 65 to 80%.
A Protocol for determining the degree of esterification of a pectin may be found on page 58 of WO-A-97/03574 (the contents of which are incorporated herein by reference). For ease of reference, this Protocol is recited at the end of the Examples section (infra) as Protocol V.
The structure of pectin, in particular the degree of esterification of pectin and the degree of block structure i.e. the degree of distribution of ester groups and free carboxyl groups in blocks, controls many of the physical properties of the pectin. Thus, modification and/or control of the degree of esterification and degree of block structure may be important.
The degree of esterification and/or degree of block structure may be modified and/or controlled by any method. Examples of suitable methods are acid hydrolysis, alkali hydrolysis, use of other chemical de-esterification agents, or by use of enzymes. Suitable enzymes can be obtained from plants or micro-organisms such as bacteria, yeast or fungi. The enzymes disclosed in the review prepared by Pilnik and Voragen (Food Enzymology, Ed.: P. F. Fox; Elsevier; (1991); pp: 303-337) may be used.
Preferably, the degree of esterification of the pectin composition is modified and/or controlled by use of a pectin methylesterase (EC 3.1.1.11), otherwise referred to as a PME. PMEs de-esterify HE pectins to LE pectins or pectic acids.
The use of PMEs is advantageous because PME activity produces free carboxyl groups and free methanol. The increase in free carboxyl groups and thus the degree of esterification can be easily monitored by automatic titration.
For example, the degree of esterification of the calcium sensitive pectin population is modified and/or controlled in accordance with a process described in WO 98/47391 (which claims priority from British Patent Application No 9708278.8).
Preferably the pectin composition is obtainable or is obtained by fractionation of a pectin or a pectin composition. Using fractionation techniques a pectin composition may be obtained which is enriched in one or more specific calcium sensitive pectin populations.
Preferably the pectin composition is obtainable or is obtained by selecting peels from a citrus fruit, for instance lime and/or lemon, and extracting the pectin by a process comprising the steps of:
Extraction
Mixing the peel with water at a water:peel ratio of 21:1
Adjusting, if necessary, the pH to 1.9-2.3 using nitric acid
Heating to a temperature of 68-71xc2x0 C. for 3-6 hours
Filtration
After extraction the pectin solution is filtered.
Precipitation
Reducing the temperature to 36-40xc2x0 C.
Adjusting the pH to 2.6-2.9
Adding isopropyl alcohol until precipitation occurs. Typically an isopropyl alcohol concentration of 49-58 w/w % is required.
Post treatments
After precipitation the pectin may be dried and/or milled.
Preferably, the use of the present invention provides an aqueous composition.
Thus, in a third aspect of the present invention there is provided an aqueous composition prepared in accordance with the use of the present invention.
The aqueous composition of the present invention may comprise one or more other components, such as one or more suitable food ingredients. Typical food ingredients include any one or more of a salt, a protein, an acidxe2x80x94such as citric acidxe2x80x94or a sugarxe2x80x94such as sucrose, glucose or invert sugarxe2x80x94or fruitxe2x80x94or enzymes.
The present invention can be used in the preparation of pharmaceutical products, foodstuffs and non-food products.
Typical pharmaceutical products include clinical nutritive products (enteral products and other liquid products).
Typical non-food products include de-icing agents and paints.
The term xe2x80x9cfoodstuffxe2x80x9d can include food for human and/or animal consumption.
Typical foodstuffs include jams, fruit preparations, fruit fillings, ripples, fruit sauces, stewed fruit, dairy products (such as milk products and ice cream), fine foods (such as salad dressings, ketchup, vinaigrette dressings and soups), meat products, poultry products, fish products and bakery products. The foodstuff may be a beverage. The beverage may be a drinking yoghurt, a fruit juice, a beverage concentrate or a fruit based beverage.
The present invention may be used in the preparation of a starting reagent or an intermediate in the preparation of a foodstuff.
Alternatively, present invention may be used in the preparation of a foodstuff itself.
Preferably, the pectin composition comprises no greater than 5.0 wt % of aqueous composition based on the total weight of the aqueous composition. More preferably, the pectin composition comprises no greater than 0.1-1.5 wt % of aqueous composition based on the total weight of the aqueous composition.
Preferably, the pectin composition and/or the aqueous composition further comprises one or more metal ions. Preferably, the one or more metal ions comprise metal ions selected from ions of elements of Group II of the Periodic Table. Yet more preferably, the one or more metal ions comprise at least Ca2+ ions.
In a further preferred embodiment, the pectin composition and/or aqueous composition comprises 25-300 mg of metal ions per gram of pectin. In yet a further preferred embodiment, the pectin composition and/or aqueous composition comprises 50-150 mg of metal ions per gram of pectin.
In a further preferred embodiment, the pectin composition and/or aqueous composition comprises 25-300 mg of Ca2+ ions per gram of pectin. In yet a further preferred embodiment, the pectin composition and/or aqueous composition comprises 50-150 mg of Ca2+ ions per gram of pectin.
In the above embodiment the metal ions may be introduced in to the pectin composition by adding the metal ions to the pectin composition during production thereof or it can be added to the dry pectin composition afterwards. In one alternative, the metal ions may be introduced in to the pectin composition by adding the metal ions to the pectin composition in the presence of water.
The metal ions may be introduced in to the aqueous composition by adding the metal ions directly thereto before or after the introduction of the pectin composition in to the aqueous composition.
The metal ions, preferably calcium, may be added as a metal ion salt. For example the metal ion may be added in the citrate form of the metal, for example, calcium citrate.
An example of the combination of metal ions and pectin composition in accordance with the present invention to provide an aqueous composition in accordance is given below:
1) A pectin with a pH value of 5 is mixed with calcium citrate
2) The mixture is dissolved in water. Under the pH conditions i.e. a pH of 5, only the pectin will dissolve.
3) The pH is lowered to a level below 4. On lowering pH the calcium citrate will dissolve, releasing the calcium. Once the calcium is released it will become available and an aqueous composition exhibiting high yield stress characteristics without substantial gelation is obtained.
It is essential that the pectin composition for use in the present invention comprises a population of pectin that is calcium sensitive. However, the pectin composition for use in the present invention may further comprise at least one calcium insensitive pectin.
Preferably, the population of pectin that is calcium sensitive comprises at least 40 wt % of the pectin composition. More preferably, the population of pectin that is calcium sensitive comprises at least 50 wt % of the pectin composition. More preferably, the population of pectin that is calcium sensitive comprises at least 60 wt % of the pectin composition. More preferably, the population of pectin that is calcium sensitive comprises at least 70 wt % of the pectin composition. Yet more preferably, the population of pectin that is calcium sensitive comprises at least 80 wt % of the pectin composition.
The proportion of the pectin composition that is calcium sensitive may be determined in accordance with the method of Protocol VI. Protocol VI is recited at the end of the Examples section (infra).
Preferably, the pectin composition has a reduced viscosity of at least 0.25 L/g. More preferably, the pectin composition has a reduced viscosity of at least 0.375 L/g. Yet more preferably, the pectin composition has a reduced viscosity of at least 0.50 L/g. Reduced viscosity may be measured in accordance with Protocol VII. Protocol VII is recited at the end of the Examples section (infra).
In the present specification we have described that the present invention relates to the use of a pectin composition. However, the present invention also encompasses the use of any polysaccharide to provide the advantageous properties of the present invention. Thus, in a broad aspect, the present invention provides the use of a polysaccharide composition to prepare an aqueous composition having high yield stress characteristics without substantial gelation; wherein the polysaccharide composition is capable of imparting high yield stress characteristics to an aqueous composition without causing substantial gelation of the aqueous composition.
Alternatively, in a broad aspect the present invention provides the use of a composition comprising a pectin isostere to prepare an aqueous composition having high yield stress characteristics without substantial gelation, wherein the pectin isostere composition is capable of imparting high yield stress characteristics to an aqueous composition without causing substantial gelation of the aqueous composition.
In a further broad aspect the present invention provides a pectin composition, wherein the pectin composition comprises at least a population of pectin that is calcium sensitive; wherein the pectin composition is capable of imparting high yield stress characteristics to an aqueous environment without causing substantial gelation of the aqueous environment. In this broad aspect the present invention further provides a process for preparing an aqueous composition, preferably a foodstuff, comprising the step of combining an aqueous medium with a pectin composition, wherein the pectin composition comprises at least a population of pectin that is calcium sensitive; wherein the pectin composition is capable of imparting high yield stress characteristics to an aqueous environment without causing substantial gelation of the aqueous environment.